识别正在播放的音频文件的运行时间

Question

我正在开发一个简单的音频播放器，它会在我暂停/停止播放时显示音频播放了多长时间（编辑：例如，如果我在 52 秒处重新开始音乐，然后在 55 秒处暂停，则吐司说“3”）。截至目前，我正在使用这个：

long startTime = System.currentTimeMillis();
long stopTime = System.currentTimeMillis();
Toast.makeText(getApplicationContext(), "Elapsed time was " + ((stopTime - startTime)/1000) + " seconds.", Toast.LENGTH_LONG).show();}

显示时差。我遇到的问题是 startTime 是从我第一次点击播放开始的，而不是最近的时间（只是不断地计数）。

import android.media.AudioManager;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

private Button playMusic;
private MediaPlayer mediaPlayer;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mediaPlayer = new MediaPlayer();
    mediaPlayer = MediaPlayer.create(getApplicationContext(), R.raw.adele);
    mediaPlayer.setLooping(true);
    mediaPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener(){
        @Override
        public void onCompletion(MediaPlayer mp){
            int duration = mp.getCurrentPosition()/1000;
            Toast.makeText(getApplicationContext(), "Duration:" + duration + " seconds", Toast.LENGTH_LONG).show();
        }
    });

    playMusic = (Button) findViewById(R.id.playButton);
    playMusic.setOnClickListener(new View.OnClickListener(){
        long startTime = System.currentTimeMillis();
        @Override
        public void onClick(View v){

            if (mediaPlayer.isPlaying()) {
                pauseMusic();
                long stopTime = System.currentTimeMillis();
                Toast.makeText(getApplicationContext(), "Elapsed time was " + ((stopTime - startTime)/1000) + " seconds.", Toast.LENGTH_LONG).show();}
            else {
                startMusic();
            }
        }
    });

    setVolumeControlStream(AudioManager.STREAM_MUSIC);
}

public void pauseMusic(){
    if (mediaPlayer !=null){
        mediaPlayer.pause();
        playMusic.setText(getString(R.string.button_start));
    }
}

public void startMusic(){
    if (mediaPlayer != null){
        mediaPlayer.start();
        playMusic.setText(getString(R.string.button_pause));
    }
}

protected void onDestroy(){
    if (mediaPlayer !=null && mediaPlayer.isPlaying()) {
        mediaPlayer.stop();
        mediaPlayer.release();
        mediaPlayer = null;
    }
    super.onDestroy();
    }
}

Answer 1

首先将 long startTime 和 stopTime 放在 onCreate() 方法之上。现在，尝试在 onPause() 方法中添加这些代码行并像这样更改代码：

public void pauseMusic(){
    if (mediaPlayer !=null){
        mediaPlayer.pause();
        startTime=mediaPlayer.getCurrentPosition();
        playMusic.setText(getString(R.string.button_start));
    }
}